1. Technical Field
This invention relates to axial valves, that is, valves with axially moving valve elements along a longitudinal extension of the valve, the longitudinal extension being along a prevailing flow direction of fluid through the valve. The invention relates more particularly to axial electronic valves in vapor compression systems such as refrigeration systems. The invention also relates to a vapor compression system with such valve.
2. Background Art
Axial valves are well known for flow control. Axial valves have a passageway that is substantially parallel to the fluid flow path. Axial valves typically comprise an actuator, and the actuator can be a stepper motor with a stator and a rotor and a stem.
Known axial valves are commonly rather complex. The rotational movement of the rotor is transformed to a linear moving stem, the stem in one end has a head. When the stem is moved in one direction the head acts with a valve seat to close the valve orifice for fluid passage, and when the stem is moved in the opposite direction, the head is moved away from the valve seat to open for fluid passage through the orifice. The axial valve has many parts making the assembly complicated and requiring critical process control to reduce rejects. The many parts of the valve increase the risk of failure of parts of the valve due to productions failures or due to malfunction between the many parts during operation of the valve.
Furthermore, the forces acting from the flow of fluid, when the valve is operating, can be significant and may hamper movement of the movable parts. The flow-forces can thereby act as a barrier for reaching high capacities or high differential pressures between inlet and outlet of the valve.